The present invention relates generally to the field of chemical vapor deposition, and specifically, to hot wire chemical vapor deposition (HWCVD).
The HWCVD process typically entails decomposition of a precursor gas on the surface of a metal catalyst filament whereby product(s) of the decomposition reaction are deposited on a substrate. However, with continued use, filaments (e.g. tungsten filaments) typically degrade and change surface chemistry. For example, precursor species, such as silane, can react with the tungsten filament surface to form a layer of tungsten silicide and/or amorphous silicon thereon. Consequently, the deposition conditions can also change since the surface chemistry of the filaments is altered. In order to maintain a more constant reaction condition during a deposition run or during successive depositions, it would be beneficial to deal with this issue.